The present invention relates to frozen biocidal compositions useful in preserving perishable articles and, in particular, frozen biocidal compositions comprising a sodium chlorite solution.
The use of various chlorine-containing compounds as biocidal agents is known. The literature contains references to the use of chlorine gas, hypochlorites, and chlorine dioxide as materials that can be used to kill microorganisms. A number of patents teach that chlorine dioxide is an effective microbicide, and that it has powerful and effective oxidizing characteristics useful in killing various microorganisms when used in various applications, such as surface disinfecting, water treatment, wound healing, etc. However, chlorine dioxide has many shortcomings. For example, it is a potentially hazardous material that is generally difficult to produce and apply where needed.
Preservation of perishable articles is a major concern for a number of industries, including the agriculture, fishing, and meat-related industries. During the time of harvesting, catching, transporting, and/or storage of perishable articles, particularly food articles, pathogenic and spoilage bacteria continue to multiply exponentially.
Many agents have been tested as potential biocides for use against such spoilage. Most methods incorporate, alone or in combination, various mechanical, chemical, electrical, etc. means, including the use of ice or refrigeration, protective atmospheres and packaging, ionizing radiation, and the use of various chlorine-containing or chlorine-derived compounds. Such compounds and methods have met with mixed success, and often exacerbate the original problem, due to the toxicity of such compounds and methods. Another issue is the relatively high cost associated with the use of such known methods.
U.S. Pat. No. 4,880,638, the entire contents of which are incorporated by reference herein, discloses compositions that do not produce measurable amounts of chlorine dioxide, but do generate interactive intermediates. Further, commonly assigned U.S. Pat. No. 5,830,511, the entire contents of which are incorporated by reference herein, discloses the usefulness of a chlorite-containing composition orally administered to livestock in a therapeutic and production method for enhancing feed utilization and decreasing mortality rate in healthy and infected food animals.
There remains a need in the art for a biocidal product suitable for use on perishable articles that is: 1) benign to the perishable article; 2) less expensive; 3) minimally toxic; and 4) at least as effective as known methods of preserving perishables.
The present invention provides biocidal compositions comprising a frozen aqueous solution containing a plurality of ions selected from the group consisting of halide and oxyhalide ions. More particularly, the present invention is directed to a frozen aqueous solution of a pH-buffered composition comprising halide and oxyhalide ions, wherein the pH of the solution is at least about 6.0 or higher. In one embodiment, the solution comprises water, chlorite ions, chloride ions and chlorate ions. The solution may also include one or more buffering agents and/or chlorine dioxide-inhibiting agents.
The present invention also provides a method of preserving perishable articles. In the method of the invention, a frozen aqueous solution comprising a pH-buffered composition is contacted with a perishable article. The frozen aqueous solution may be in the form of larger solid blocks or in smaller particulate form, such as shaved or crushed ice. In another embodiment, the aqueous solution of the invention is contacted with the perishable article while the solution is in liquid form and thereafter the solution and article are frozen together.
The invention also provides a preserved perishable article comprising a perishable article in contact with a frozen solution of a pH-buffered composition comprising halide and oxyhalide ions, wherein the pH of the solution is at least about 6.0.